in libya's president said 50 people have been arrested in the attack that kill kd the u.s. ambassador and three members of his team. at the same time there are diverging views on who is responsible for the attack. anna werner begins our coverage from washington. >> reporter: in the five days since ambassador chris stevens and three other americans were killed in libya, violent protests against the u.s. have reached more than 50 cities. clashes with security forces outside the u.s. consulate in karachi, pakistan, today, left at least one protestor dead and eight others injured. this weekend the u.s. was busy evacuating nonessential personnel from sudan and tunisia, urging american citizens to get out. today on "face the nation" libyan president mohammed el magariaf said he believes last week's deadly attack in benghazi was premeditated. >> the way the perpetrators acted, moved, this leaves us with no doubt that this was preplanned, predetermined. >> reporter: but u.s. ambassador to the u.n. susan rice disagrees telling bob schieffer that it was a spontaneous protest hijacked